Photodynamic therapy (PDT) was given to 20 patients who had recurring superficial tumours after unsuccessful application of other treatments. The phototherapeutic results were evaluated by check-ups at 3 month intervals (endoscopy, cytology, bladder mapping, renal ultrasonography) and computed tomography (CT) examination at 8-13 month intervals. In six patients treated with PDT no tumour recurrence was found over the whole observation period up to nearly 5 years. Four patients remained free of tumour (12 and 14 months) after repeated transurethral resection (TUR) and Nd:YAG laser therapy following PDT. Due to an initial application of insufficient irradiation, four patients required a second photodynamic treatment. In one of these cases a circumscribed dysplasia which appeared at the left ostium 26 months following PDT was treated successfully using the Nd:YAG laser following TUR. In six patients slight mucosal atypia persisted for a period of at least 2.5 years. One cystectomy had to be performed because of bladder shrinkage. The dissected bladder was free of tumour. According to these preliminary results, PDT with strict patient selection (worst case situation with recommended cystectomy) is justified in the case of recurrent superficial TIS bladder carcinoma.